the.com/proofread

means To read through written text carefully in order to find and fix errors in spelling, grammar, punctuation, and formatting before it goes out.

from A compound of "proof" and "read." The "proof" here is the printer's sense: a trial sheet pulled from set type so it could be checked before the full run. That meaning of "proof" descends from Latin "probare," to test or prove. So a proofreader was literally someone who read the proofs — testing the page for flaws before the press committed them to permanence. The figurative reading-for-errors sense grew naturally out of that printing-house chore.